A002858 - cp's OEIS frontend

A002858 Ulam numbers: a(1) = 1; a(2) = 2; for n>2, a(n) = least number > a(n-1) which is a unique sum of two distinct earlier terms.

n	a(n)
1	1
2	2
3	3
4	4
5	6
6	8
7	11
8	13
9	16
10	18
11	26
12	28
13	36
14	38
15	47
16	48
17	53
18	57
19	62
20	69
21	72
22	77
23	82
24	87
25	97
26	99
27	102
28	106
29	114
30	126
31	131
32	138
33	145
34	148
35	155
36	175
37	177
38	180
39	182
40	189
41	197
42	206
43	209
44	219
45	221
46	236
47	238
48	241
49	243
50	253
51	258
52	260
53	273
54	282
55	309
56	316
57	319
58	324
59	339

[1, 2, 3, 4, 6, 8, 11, 13, 16, 18, 26, 28, 36, 38, 47, 48, 53, 57, 62, 69, 72, 77, 82, 87, 97, 99, 102, 106, 114, 126, 131, 138, 145, 148, 155, 175, 177, 180, 182, 189, 197, 206, 209, 219, 221, 236, 238, 241, 243, 253, 258, 260, 273, 282, 309, 316, 319, 324, 339]

cp's OEIS Frontend

A002858 Ulam numbers: a(1) = 1; a(2) = 2; for n>2, a(n) = least number > a(n-1) which is a unique sum of two distinct earlier terms.

Table of values

List of values

n	a(n)
1	1
2	2
3	3
4	4
5	6
6	8
7	11
8	13
9	16
10	18
11	26
12	28
13	36
14	38
15	47
16	48
17	53
18	57
19	62
20	69
21	72
22	77
23	82
24	87
25	97
26	99
27	102
28	106
29	114
30	126
31	131
32	138
33	145
34	148
35	155
36	175
37	177
38	180
39	182
40	189
41	197
42	206
43	209
44	219
45	221
46	236
47	238
48	241
49	243
50	253
51	258
52	260
53	273
54	282
55	309
56	316
57	319
58	324
59	339

n	a(n)
1	1
2	2
3	3
4	4
5	6
6	8
7	11
8	13
9	16
10	18
11	26
12	28
13	36
14	38
15	47
16	48
17	53
18	57
19	62
20	69
21	72
22	77
23	82
24	87
25	97
26	99
27	102
28	106
29	114
30	126
31	131
32	138
33	145
34	148
35	155
36	175
37	177
38	180
39	182
40	189
41	197
42	206
43	209
44	219
45	221
46	236
47	238
48	241
49	243
50	253
51	258
52	260
53	273
54	282
55	309
56	316
57	319
58	324
59	339

n	a(n)
1	1
2	2
3	3
4	4
5	6
6	8
7	11
8	13
9	16
10	18
11	26
12	28
13	36
14	38
15	47
16	48
17	53
18	57
19	62
20	69
21	72
22	77
23	82
24	87
25	97
26	99
27	102
28	106
29	114
30	126
31	131
32	138
33	145
34	148
35	155
36	175
37	177
38	180
39	182
40	189
41	197
42	206
43	209
44	219
45	221
46	236
47	238
48	241
49	243
50	253
51	258
52	260
53	273
54	282
55	309
56	316
57	319
58	324
59	339